<> The crater was created instantly when a 50m, 150,000-ton meteor slammed into the desert about 50,000 years ago. Terraces are a common feature of many large craters---for another example, look at the crater Theophilus. - Lunar and Planetary Institute The impactor is shattered into small pieces and may melt or vaporize. Image from the Mars Global Surveyor, courtesy of the Lunar and Planetary Institute. The 50 km-diameter Mathilde asteroid has a mean density of 1.3 g/cm only and is considered a kind of rubble pile. This impact is thought to have triggered fires and tsunamis and created a cloud of dust and water vapor that enveloped the globe in a matter of days, resulting in fluctuating global climate changes. A stone-into-mud crater demonstrates the difference between it and a hypervelocity crater (Fig. Justify your answer. The contact and compression stage of impact cratering. 2) we may think it somehow formed from an identical mechanism. 4. The so-called Meteor Crater in Arizona previously held the record for largest impact crater less than 100,000 years old; it's about 49,000 to 50,000 years old and measures 0.75 miles (1.2 km) in . )y&bS_jW+|z6ADS FZM+q&+rVim#yHNO 8tU#T.f-[`of=XzuEvr+Ll[fXt 7; UGs@wc The term transient crater means the cratering process continues after the excavation flow comes to rest. What process do you think formed Reuyl crater (marked B on Figure 11.5)? Explain why you believe this is so. Arid climate and a lack of vegetation in the vicinity of Meteor Crater make it an excellent comparison site for similar-sized impact craters on Mars, Ramsey said. (Viking mosaic P-17698) 9. (not recommended in an introductory lab - you don't know who has handled or licked the sample before you).Other PropertiesFluorescence, RadioactivityRequires special equipment such as a UV lamp and geiger counter. Justify your answer. This suggests that the transient crater collapse in the modification stage is largely driven by gravity (gMoon ~ 1/6 gEarth). Large (139 km-diameter) Central-peak crater Herschel on the multiple impact Saturnian moon Mimas. Both minerals are composed of carbon (C). These are fragments or pieces of rock or minerals. Southern cratered highlands. Craters come in two flavors: those that arent caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. Consider the relationship between Ma'adim Vallis and Gusev, the 160 km diameter crater marked D. Explain what could be the origin of the material that comprises the floor of Gusev? How looks an impact crater that was produced by an oblique impact? Apart from the distinct role rarefactions waves play in the formation of the excavation flow field, they are especially relevant geologically. The large circular dark areas in the image are impact basins, created as huge impactors struck the Moon. endobj When first we see images of the famous one-kilometer (0.75-mile) bowl-shaped Barringer meteorite crater in Arizona (Fig. The faster the incoming impactor, the larger the crater. The larger size gives the foliation a slighly shiny appearance. Dark colors, such as black and dark brown, indicate a mafic or ultramafic composition. Impact cratering is the excavation of a planet's surface when it is struck by a meteoroid. Such outbursts can be violent enough that once the eruption is over, the volcano collapses in on its empty vacant magma chamber and forms a caldera, or volcanic crater. <> The ejecta blanket has lobes, which may indicate wet material was ejected, suggesting that subsurface water or melted ice was mixed into the debris. The circular shape is due to material flying out in all directions as a result of the explosion upon impact, not a result of the impactor having a circular shape (almost no impactors are spherical). Anthracite coal is generally shiny in appearance and breaks with a conchoidal fracture (broken glass also shows this type of fracture). 16. These definitions and methods are simplified. Study with Quizlet and memorize flashcards containing terms like Where do you find the thickest ejecta?, How do you think the crater rim formed?, Where would you find most of the younger material? Consider the relationship between Ma'adim Vallis and Gusev, the 160 km diameter . 14. Phyllitic foliation is composed of platy minerals that are slightly larger than those found in slaty cleavage, but generally are still too small to see with the unaided eye. eige6 Impacts are instantaneous events. On impact of a cosmic body, shock waves start from the contact point and propagate into both the underground target rocks and into the impactor. This image shows a simple crater on Mars that has no central peak or terraces around its edges. These fragments or clasts can be very fine (ash) or coarse (lapilli) or very coarse (bombs and blocks). Reuyl, an early Hesperian crater, provides evidence for diverse fluvial events; Alluvial fans, channels, orthogonally superposed deposits, fan deposits with incised channels, and large deposits suggest fluvial activity; Two sinuous ridges associated with the alluvial fan on the crater floor are the oldest features of fluvial origin This of course is primarily a matter of energy related with the projectiles mass (and therefore density) and impact velocity, and, subordinately, also a matter of the target lithology. Explain why you believe the way you do. In the following, these three stages are illustrated and described in a somewhat simplified manner. These craters are, however, decidedly not impact structures. A mystery concerning water on Mars is "Where did it go?" Its features, such as the ejecta blanket beyond its rim, are well preserved because of the crater's youth; it has not experienced extensive erosion. Valley systems cut through many of the cratered terrains of Mars and have characteristics analogous to water-cut valleys on Earth. As a rule of thumb, older surfaces have been exposed to impacting bodies (meteoroids, asteroids, and comets) for a longer period of time than younger surfaces. Much of Earth's surface is recycled through plate tectonic activity (and erosion), so Earth also has few craters. A very rough rule of thumb amounts to the order of a one-to-ten diameter ratio. Geologic processes have not erased the craters with time. Sediment is deposited in a number of environments of deposition, by both moving air and moving water. 9. 17. 5 0 obj Sedimentary rock identification is primarily based on composition. Some of this tiny debris makes it to Earth's surface and is mixed with soil and ocean sediment. Suggest some ways in which the scarp around Olympus Mons might have formed. Therefore, a simplified system is used based on texture and composition. Justify your answer. Reuyl Crater Central Peak, as seen by HiRISE. We can also see an inverted channel system, possibly ponded toward the southwest. 10 12 exemplify typical terrestrial structures. A comparable process is observed with the peculiar shock-deformed Buntsandstein conglomerates in Spain and is in more detail explainedHERE. 3 strongly resemble meteorite impact craters exhibiting a central uplift like the Tycho impact crater on Earths moon (Fig. Explain your answer. Thank you for your participation! Which is larger, and by how much? The GIF below shows the formation sequence of the model (a YouTube . Nevertheless, the resulting impact crater is more or less circular unless the angle of incidence is very low, less than 10. A central-uplift (central peak) crater (Gow, Canada, 4 km diameter). Marble is composed of calcite and will readily react to a small drop of HCl. The Vredefort impact crater, about 100 kilometers (60 miles) from Johannesburg, South Africa, was formed just a little over 2 billion years ago. What process do you think formed Reuyl crater (marked B on Figure 5)? Computing these vectors (direction and magnitude) for each point in the subsurface, a field of excavation flow with arcuate trajectories as shown in the sketch above (Fig. Fig. Four minerals that need to be identified are quartz, halite, gypsum and calcite. Explain their similarities and their differences. But no matter at what angle it makes contact, the enormous amount of kinetic energy the projectile carries immediately transfers to the target rock it hits, triggering powerful shock waves. Fig. Reuyl is a crater in the Aeolis quadrangle of Mars, located at 9.8 south latitude and 193.2 west longitude. Such outbursts can be violent enough that once the eruption is . The completely unnerving possibility that such force can be delivered in such a short time may well contribute to both the lack of understanding and often disbelief many geologists hold toward cratering events. Which of the four geologic processes do you think formed this channel? | Hesperia Planum, showing bright windstreaks associated with some of the craters. Approximately 80% of Earth's surface is less than 200 million years old, while over 99% of the Moon's surface is more than 3 billion years old. Given such drastic, far-reaching outcomes of space rock impacts, Kring said that studying crater formation holds the answer to understand not only how life on Earth began but also how it could be wiped away again in a future, perhaps inevitable, K-T event. : Impact cratering. Beware that even though an igneous rock may have a felsic composition (light color), the rock can contain dark colored minerals. More elongate craters can be produced if an impactor strikes the surface at a very low angle less than 20 degrees. Which of the four geologic processes might be responsible for the formation of Ius Chasma? }v)He|/7rw9>{W9qM~Zs.|9q7_9'o2p3kie V;\UXF}w1l`p!U,9#H{wx 0 ~ endstream endobj 103 0 obj 294 endobj 67 0 obj << /Type /Page /Parent 59 0 R /Resources 68 0 R /Contents [ 75 0 R 77 0 R 79 0 R 86 0 R 88 0 R 93 0 R 96 0 R 99 0 R ] /MediaBox [ 0 0 612 792 ] /CropBox [ 0 0 612 792 ] /Rotate 0 >> endobj 68 0 obj << /ProcSet [ /PDF /Text /ImageB ] /Font << /F2 85 0 R /F3 71 0 R /F4 91 0 R /F9 69 0 R /F12 83 0 R >> /XObject << /Im9 95 0 R >> /ExtGState << /GS1 98 0 R /GS14 101 0 R >> >> endobj 69 0 obj << /Type /Font /Subtype /Type1 /Name /F9 /FirstChar 32 /LastChar 255 /Widths [ 343 384 500 686 686 975 848 250 352 352 483 686 343 392 343 579 686 686 686 686 686 689 686 686 686 686 343 343 686 686 686 595 740 781 677 660 752 550 542 842 803 324 489 758 495 983 881 887 661 887 680 616 533 778 761 1117 789 714 707 350 579 350 686 500 402 682 682 483 682 610 388 677 661 302 302 688 302 989 661 662 682 682 453 513 360 659 623 996 712 654 559 352 579 352 686 343 781 781 660 550 881 887 778 682 682 682 682 682 682 483 610 610 610 610 302 302 302 302 661 662 662 662 662 662 659 659 659 659 686 400 686 686 686 686 686 651 800 800 940 402 604 0 1026 887 0 686 0 0 686 659 0 0 0 0 0 409 410 0 940 662 595 384 686 0 686 0 0 603 603 1000 343 781 781 887 1140 1022 500 1000 628 628 372 372 686 0 654 714 194 686 354 354 679 690 686 343 338 594 1460 781 550 781 550 550 324 324 324 324 887 887 0 887 778 778 778 302 590 549 603 539 402 457 380 539 350 590 ] /Encoding /MacRomanEncoding /BaseFont /Futura-Bold /FontDescriptor 73 0 R >> endobj 70 0 obj << /Filter /FlateDecode /Length 21345 /Length1 28684 >> stream The crater is about 1.2 kilometers (a little more than 0.5 miles) across and 200 meters (650 feet) deep. Location: 24S, 245W. Texture of sedimentary rocks in this lab will be taken to indicate origin or type of sediment found in the rock. (a) Geomorphic map of Reuyl crater. Using the following picture draw a box around the area that is shown in Figure 2. Scientists record the size and number of impact craters and how eroded they are to determine the ages and histories of different planetary surfaces. The compression stage of crater formation involves that initial exchange of energy between the projectile and the impact area. Both are black in color, and is composed of carbon. The Chicxulub crater in the Yucatan peninsula, Mexico, is not visible at the surface of the seafloor. You can help Wikipedia by expanding it. These temperatures are enough to more or less completely vaporize the impactor and a volume of the target rocks roughly comparable to the volume of the impactor, resulting in a giant expanding impact vapor plume. HYPERLINK "../Honors227/Images/10_3.jpg"Figure 3. Fig. If windstreaks are dust deposits formed downwind from the craters, what wind direction is indicated here? The image shows ring-like structures that extend to about 280 kilometers (175 miles) from the center. The force can catapult chunks of molten and solid rock hundreds of miles from the impact site this material is known as ejecta flow. Source: Google Earth. What happens to the transient crater? (Hint: remember that wind direction refers to the direction from which the wind blows.) Dual crater at the bottom of Lake Chiemsee, Bavaria (Germany) that very probably formed in the large Holocene Chiemgau impact event. 12. The result is a "bubbly" appearance. 9). 1. This icy bedrock is potentially unstable, and some impact craters may relax or fade away to unrecognition due to water ice's volatility and weak but strongly temperature dependent rheology. What geologic process do you think formed Reuyl (labeled B)? Copernicus is a large crater (93 kilometers or 60 miles wide) on the Moon. This article about an extraterrestrial geological feature is a stub. The large number of craters in this region indicates that this part of the Moon is quite ancient. Whereas volcanic craters arise from deep inside the planet, impact craters originate in outer space. A good example is diamond and graphite. When an asteroidal or cometary object strikes a planetary surface, it is traveling typically at several tens of kilometres per secondmany times the speed of sound.A collision at such extreme speeds is called a hypervelocity impact. Obsidian is volcanic glass which erupts as a lava flow. 4) What process do you think formed Apollinaris Patera, marked A? h_X CJ h_X 5B* CJ ph h \ In concurrence with this result, the crater age . 7 0 obj ), 1987, Glossary of Geology. Sometimes the force of the impact is great enough to melt some of the local rock. <>>> This lab is an adaptation of an adaptation by Richard Harwood based upon the original NASA resource: A Teacher's Guide with Activities in Physical and Earth Sciences for Planetary Geology,: National Aeronautics and Space Administration, 1998, EG-1998-03-109, p. 238. Based on the number and morphology of craters, is this a relatively old or young region of Mars? 19. During the final modification phase, the remainder of ejecta partially refills and rings the crater site, and debris forms a rich mineral composite called breccia. Pegmatitic texture is composed of very large crystals (larger than 2-3 cm). Quite a few interesting questions may remain open. 3), and the central mound in the craters shown in Fig. e. Image source: NASA. Look this information up in your lab manual once the mineral has been identified.StreakColor of the mineral when it is powdered.Grind a small amount of a mineral into a powder on a porcelain streak plate and determine the color of the powder.TasteNerve ending reaction in the tongue to different chemicals.Lick the mineral. <> Further identification of non-foliated rocks is dependent on the composition of the minerals or components in the rock. This crater is believed to have formed when an asteroid struck Earth 65 million years ago. Terms of Use, Copyright document.write(new Date().getFullYear()); endobj Ius Chasma, part of the Valles Marineris system. Why does the Moon have so many craters while Earth has so few? Cooling of the magma can occur beneath the surface (plutonic) or on the surface (volcanic). by lava flows that obscured the older craters. Fig. This means that our own planet is one of the youngest in the Solar System. Ma'adim Vallis is the channel in the southeast part of the photograph, marked C. Which of the four processes do you think formed Ma'adim Vallis? 18. The Measurer should measure from the ground to how high the rock is, and ask the Recorder to write down that height under the heading "Meteor 1, Trial 1". Impact shock waves are characterized by an instantaneous onset of extreme pressures (up to the order of megabars) and extreme temperatures (up to 10,000 degrees or more) on release of the pressure. Look for areas where the light reflects from planar surfaces. Martian shield volcano, Olympus Mons. The two most notable are obsidian and dunite. Although Mars does not have plate tectonics like the Earth, there are many tectonic features that show its surface has been deformed. stream > h] bjbj!! 1). The first is called erosion. As a result, there are only around 160 known impact craters in existence today (though there are surely more that haven't been discovered). <> Gypsum is relatively soft (Hardness =2) and can be scratched easily with a fingernail. There are some interesting erosional signs in this observation, which will make for a good comparison with other intracrater fans and fluvial sedimentary landforms.